.\" Copyright 1998 Andries E. Brouwer (aeb@cwi.nl)
.\" Copyright 2007 Karel Zak <kzak@redhat.com>
.\"
.\" May be distributed under the GNU General Public License
.TH BLOCKDEV 8 "August 2010" "util-linux" "System Administration"
.SH NAME
blockdev \- call block device ioctls from the command line
.SH SYNOPSIS
.B blockdev
.RB [ \-q ]
.RB [ \-v ]
.I command
.RI [ command \&...\&]
.I device
.RI [ device \&...\&]
.br
.B blockdev
.B \-\-report
.RI [ device \&...\&]
.SH DESCRIPTION
The utility
.B blockdev
allows one to call block device ioctls from the command line.
.SH OPTIONS
.IP "\fB\-V\fP"
Print version and exit.
.IP "\fB\-q\fP"
Be quiet.
.IP "\fB\-v\fP"
Be verbose.
.IP "\fB\-\-report\fP"
Print a report for the specified device. It is possible to give multiple
devices. If none is given, all devices which appear in /proc/partitions are
shown. Note that the partition StartSec is in 512-byte sectors.
.SH COMMANDS
It is possible to give multiple devices and multiple commands.
.IP "\fB\-\-flushbufs\fP"
Flush buffers.
.IP "\fB\-\-getalignoff\fP"
Get alignment offset.
.IP "\fB\-\-getbsz\fP"
Print blocksize in bytes.
.IP "\fB\-\-getdiscardzeroes\fP"
Get discard zeroes support status.
.IP "\fB\-\-getfra\fP"
Get filesystem readahead in 512-byte sectors.
.IP "\fB\-\-getiomin\fP"
Get minimum I/O size.
.IP "\fB\-\-getioopt\fP"
Get optimal I/O size.
.IP "\fB\-\-getmaxsect\fP"
Get max sectors per request
.IP "\fB\-\-getpbsz\fP"
Get physical block (sector) size.
.IP "\fB\-\-getra\fP"
Print readahead (in 512-byte sectors).
.IP "\fB\-\-getro\fP"
Get read-only. Print 1 if the device is read-only, 0 otherwise.
.IP "\fB\-\-getsize64\fP"
Print device size in bytes.
.IP "\fB\-\-getsize\fP"
Print device size (32-bit!) in sectors. Deprecated in favor of the \-\-getsz option.
.IP "\fB\-\-getss\fP"
Print sector size in bytes \(en usually 512.
.IP "\fB\-\-getsz\fP"
Get size in 512-byte sectors.
.IP "\fB\-\-rereadpt\fP"
Reread partition table
.IP "\fB\-\-setbsz\fP \fIbytes\fP"
Set blocksize. Note that the block size is specific to the current file
descriptor opening the block device, so the change of block size only persists
for as long as blockdev has the device open, and is lost once blockdev exits.
.IP "\fB\-\-setfra\fP \fIsectors\fP"
Set filesystem readahead (same like \-\-setra on 2.6 kernels).
.IP "\fB\-\-setra\fP \fIsectors\fP"
Set readahead (in 512-byte sectors).
.IP "\fB\-\-setro\fP"
Set read-only.
.IP "\fB\-\-setrw\fP"
Set read-write.
.SH AUTHOR
blockdev was written by Andries E.\& Brouwer and rewritten by Karel Zak.
.SH AVAILABILITY
The blockdev command is part of the util-linux package and is available from
https://www.kernel.org/pub/linux/utils/util-linux/.
